The present invention relates to a generator of strong synchronous current pulse on parallel outputs. The term strong current pulses is understood to mean a pulse, whose intensity is approximately 10 kiloamperes and whose half-intensity width is a few microseconds. Such a current pulse supplied on an electric line makes it possible to simulate the injection of a current pulse due to a strong electromagnetic pulse. The generator according to the invention supplying synchronous current pulses on several parallel outputs, more particularly, makes it possible to test electrical devices connected to a polyphase mains, e.g. a low voltage three-phase mains.
In the case of a low voltage mains, the electromagnetic pulse injecting a parasitic current pulse in common mode into said mains can be represented by an equivalent Norton generator with the following characteristics:
short-circuit current: I=30 kA PA1 half-intensity width: t.sub.h =2 .mu.s
A current generator with a single output having these characteristics is known, but said generator suffers from several disadvantages. It must in particular be equipped with protective shielding to absorb the radiation due to the very high voltage from a source supplying, e.g. 300 kV. As a result of the shielding the generator has a considerable weight and size making it difficult to transport. Thus, the electrical equipments which it is wished to test must be moved from this place of installation to the laboratory where the generator is located. Moreover, the known generator is complex and therefore costly.
Research has been carried out on the effect of the shape of the current pulse on the behavior of an electrical apparatus receiving said pulse. This research has been carried out, more particularly, in the case where the apparatus to be tested is a protective system located between a low voltage mains and electrical equipment to be protected.
Such a protective system is described in French patent application No. 84 06062, filed on Apr. 17 1984. It essentially comprises a clipper, whose function is to tap off most of the energy of the pulse of the mains line and a low-pass filter, whose function is to attenuate the intensity of the disturbance in the high frequency range.
The behavior of such a protective system in the presence of a current pulse produced by an intense electromagnetic pulse is essentially a function of two parameters of the said pulse, which are, on the one hand, its slope in both voltage and current and, on the other, its half-intensity width.
The slope of the pulse conditions the dynamic response of the clipper. The voltage slope determines the dynamic breakdown voltage of the clipper and the intensity slope determines the voltage developed at the terminals of the circuit. With regards to the half-intensity width of the injected current pulse, its frequency spectrum influences the response of the low-pass filter.
A current pulse generator is known, which supplies a current pulse, whose slope and half-intensity width are representative of a strong electromagnetic pulse. This generator is simpler than the preceding generator, because all the parameters of the current pulse are not reproduced. However, it requires a 100 kV voltage source for producing the current pulse. Thus, like the preceding generator, it requires protective shielding against the radiation of said voltage source.
Moreover, the two known generators described above also suffer from an important disadvantage for the common mode test on polyphase mains. More particularly, these generators have a single output. Consequently, for use on a polyphase mains, they must be equipped with a capacitive decoupling system in order that the pulse produced is distributed over each phase of the mains in question.